Modification of Shear Stress Transport Turbulence Model Using Helicity for Predicting Corner Separation Flow in a Linear Compressor Cascade

Abstract Three-dimensional corner separation significantly affects compressor performance, but turbulence models struggle to predict it accurately. This paper assesses the capability of the original shear stress transport (SST) turbulence model to predict the corner separation in a linear highly loaded prescribed velocity distribution (PVD) compressor cascade. Modifications for streamline curvature, Menter’s production limiter, and the Kato-Launder production term are examined. Comparisons with experimental data show that the original SST model and the SST model with different modifications can predict the corner flow well at an incidence angle of −7 deg, where the corner separation is small. However, all the models overpredict the extent of the flow separation when the corner separation is larger, at an incidence angle of 0 deg. The SST model is then modified using the helicity to take account of the energy backscatter, which previous studies have shown to be important in the corner separation regions of compressors. A Reynolds stress model (RSM) is also used for comparison. By comparing the numerical results with experiments and RSM results, it can be concluded that sensitizing the SST model to helicity can greatly improve the predictive accuracy for simulating the corner separation flow. The accuracy is quite competitive with the RSM, whereas in terms of computational cost and robustness it is superior to the RSM.

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Experimental and Numerical Investigation on the Aerodynamic Performance of a Compressor Cascade Using Blended Blade and End Wall

Volume 2B: Turbomachinery ◽

10.1115/gt2017-63879 ◽

2017 ◽

Cited By ~ 1

Author(s):

Jiabin Li ◽

Lucheng Ji ◽

Weilin Yi

Keyword(s):

Wind Tunnel ◽

Flow Field ◽

Turbulence Model ◽

Numerical Study ◽

Incidence Angle ◽

Good Effect ◽

Compressor Cascade ◽

Corner Separation ◽

Sst Turbulence Model ◽

End Wall

Nowadays, the corner separation, occurring near the corner region formed by the suction surface of blade and end wall, has been an important limitation for the increasing of the aerodynamic loading in the compressor. The previous numerical studies indicate that the Blended Blade and End Wall (BBEW) technology is useful in delaying, or reducing, or even eliminating the corner separation. To further validate the concept, this paper presents combined experimental and numerical investigations on a BBEW cascade and its prototype. Firstly, the NACA65 linear compressor cascade with the turning angle 42 degrees was designed and tested in a low-speed wind tunnel. Then, the cascade with blended blade and end wall design was made and tested in the same wind tunnel. The experimental results show that the design of blended blade and end wall can improve the performance of the cascade when the incidence angle was positive or at the design point, and the total pressure loss coefficient was reduced by 7%–8%. The performance improvement mainly located from 10%–25% span heights. Secondly, based on the experimental data, the numerical study made by our internal code Turbo-CFD shows the difference of the simulation precision of the results, obtained from four different turbulence model after the mesh independence test. The four turbulence model is Spalart-Allmaras model, standard k-ε model, standard k-ω model, and shear stress transport k-ω model. For this case, the SST turbulence model has better performance compared with others. Thirdly, based on the results which were calculated with the turbulence model SST, the effect of the blended blade and end wall design was discussed. The numerical study shows that the design with the blended blade and end wall can have a good effect on the corner flow of the cascade. The strong three-dimensional corner separation, caused by the accumulation of the flow happening at the trail of the suction side was avoided, and the flow losses of the prototype cascade were reduced. Above all, the experiment shows that the design with blended blade and end wall can improve the performance of the cascade. Compared with the experiment data, the SST turbulence model shows the best results of the flow field. Based on the numerical results, the details of the flow field and the effect of the blended blade and end wall design on the corner separation are discussed and analyzed.

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Unsteady lattice Boltzmann simulations of corner separation in a compressor cascade

Journal of Turbomachinery ◽

10.1115/1.4052017 ◽

2021 ◽

pp. 1-30

Author(s):

Jerome Boudet ◽

Emmanuel Lévêque ◽

Hatem Touil

Keyword(s):

Boundary Layer ◽

Lattice Boltzmann ◽

Good Description ◽

Correction Term ◽

Computational Cost ◽

Transition To Turbulence ◽

Separation Flow ◽

Compressor Cascade ◽

Corner Separation ◽

Lattice Boltzmann Simulations

Abstract Lattice-Boltzmann simulations of corner separation flow in a compressor cascade are presented. The lattice Boltzmann approach is rather new in the context of turbomachinery and the configuration is known to be particularly challenging for turbulence modelling. The present methodology is characterized by a quasi-autonomous meshing strategy and a limited computational cost (a net ratio of 5 compared to a previous finite-volume compressible Navier-Stokes simulation). The simulation of the reference case (4° incidence) shows a good agreement with the experimental data concerning the wall pressure distribution or the distribution of losses. A good description is also obtained when incidence angle is increased to 7°, with a span-wise development of the separation. Subsequently, the methodology is used to investigate the sensitivity of the flow to the end-wall boundary-layer thickness. A thinner boundary-layer results in a smaller corner separation, but not a complete elimination. Finally, the ingredients of the wall modelling are analysed in details. On the one hand, the curvature correction term promotes transition to turbulence on the blade suction side and avoids a spurious separation. On the other hand, the addition of the pressure-gradient correction term allows a wider and more realistic corner separation.

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An Improved Shear Stress Transport(SST) Model for High Speed Flows

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.229-231.625 ◽

2012 ◽

Vol 229-231 ◽

pp. 625-629

Author(s):

Jing Yuan Liu ◽

Wen Qiang Cheng

Keyword(s):

Boundary Layer ◽

Shear Stress ◽

Turbulence Model ◽

High Speed ◽

Correction Term ◽

Plate Boundary ◽

Experimental Results ◽

Tvd Scheme ◽

Shear Stress Transport ◽

Sst Model

An improved Shear Stress Transport(SST) model, which allows for the compressible corrections, is proposed in this study. Numerical scheme was established by taking advantage of the improved Total Variation Diminishing (TVD) scheme and by applying implicit scheme to the negative source terms of the turbulence model. Hypersonic flat-plate boundary-layer flows and hypersonic compression ramp flows marked with separation, reattachment and shock/boundary-layer interactions are then computed. The comparisons between the computational results, the experimental results and the semi-empirical formulations show that the compressible correction term of the SST turbulence model is the scalar product of the weighted density average of the turbulent fluctuating velocity and the pressure gradients of the average flow field correlation quantities. In addition, for flow with separation and without separation, calculation results of wall pressures, friction coefficients and wall heat transfer rate distributions using the improved model and established scheme agree better with the experimental results than that using the original SST model.

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Investigation of the Flow in Valveless Pumps

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.427-429.316 ◽

2013 ◽

Vol 427-429 ◽

pp. 316-319

Author(s):

Lan Bai ◽

Li Na Guan ◽

Yue Gang Luo

Keyword(s):

Shear Stress ◽

Laminar Flow ◽

Numerical Simulations ◽

Turbulence Model ◽

Pressure Loss ◽

Loss Coefficient ◽

Separation Flow ◽

Pressure Loss Coefficient ◽

Shear Stress Transport ◽

Valveless Pumps

An investigation of flow in valveless micropumps is presented. Numerical simulations are done using ANSYS. It is found that both laminar flow and turbulence phenomena would occurs in the diffuser/nozzle element. And SST (shear stress transport) turbulence model is chosen to be the most appropriate turbulence model,The simulations show when the opening angel gets bigger, the flow in the micropump, especially in the diffuser/nozzle becomes unsteady. When separation flow of fluid appears, pressure loss coefficient decreases rapidly.

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Evaluation of the Shear-Stress Transport Turbulence Model for Heat Transfer Applications

41st Aerospace Sciences Meeting and Exhibit ◽

10.2514/6.2003-769 ◽

2003 ◽

Cited By ~ 3

Author(s):

Xiao-Ling Tong ◽

Edward Luke ◽

Lin Tang

Keyword(s):

Heat Transfer ◽

Shear Stress ◽

Turbulence Model ◽

Shear Stress Transport

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LES Investigation of Boussinesq Constitutive Relation Validity in a Corner Separation Flow

Volume 2C: Turbomachinery ◽

10.1115/gt2018-75792 ◽

2018 ◽

Author(s):

Jean-François Monier ◽

Nicolas Poujol ◽

Mathieu Laurent ◽

Feng Gao ◽

Jérôme Boudet ◽

...

Keyword(s):

Strain Rate ◽

Stress Tensor ◽

Reynolds Stress ◽

Constitutive Relation ◽

Strain Rate Tensor ◽

Separation Flow ◽

Compressor Cascade ◽

Corner Separation ◽

Reynolds Stress Tensor ◽

Mean Strain

The present study aims at analysing the Boussinesq constitutive relation validity in a corner separation flow of a compressor cascade. The Boussinesq constitutive relation is commonly used in Reynolds-averaged Navier-Stokes (RANS) simulations for turbomachinery design. It assumes an alignment between the Reynolds stress tensor and the zero-trace mean strain-rate tensor. An indicator that measures the alignment between these tensors is used to test the validity of this assumption in a high fidelity large-eddy simulation. Eddy-viscosities are also computed using the LES database and compared. A large-eddy simulation (LES) of a LMFA-NACA65 compressor cascade, in which a corner separation is present, is considered as reference. With LES, both the Reynolds stress tensor and the mean strain-rate tensor are known, which allows the construction of the indicator and the eddy-viscosities. Two constitutive relations are evaluated. The first one is the Boussinesq constitutive relation, while the second one is the quadratic constitutive relation (QCR), expected to render more anisotropy, thus to present a better alignment between the tensors. The Boussinesq constitutive relation is rarely valid, but the QCR tends to improve the alignment. The improvement is mainly present at the inlet, upstream of the corner separation. At the outlet, the correction is milder. The eddy-viscosity built with the LES results are of the same order of magnitude as those built as the ratio of the turbulent kinetic energy k and the turbulence specific dissipation rate ω. They also show that the main impact of the QCR is to rotate the mean strain-rate tensor in order to realign it with the Reynolds stress tensor, without dilating it.

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Sensitivity Studies of Shear Stress Transport Turbulence Model Parameters on the Prediction of Seven-Rod Bundle Benchmark Experiments

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4031035 ◽

2015 ◽

Vol 2 (1) ◽

Cited By ~ 2

Author(s):

Cale Bergmann ◽

S. Ormiston ◽

V. Chatoorgoon

Keyword(s):

Shear Stress ◽

Turbulence Model ◽

Turbulence Modeling ◽

Sensitivity Study ◽

Model Parameters ◽

Rod Bundle ◽

Shear Stress Transport ◽

Sst Turbulence Model ◽

Sensitivity Studies ◽

Two Parameters

This paper reports the findings of a sensitivity study of parameters in the shear stress transport (SST) turbulence model in a commercial computational fluid dynamics (CFD) code to predict an experiment from the Generation IV International Forum Supercritical-Water-Cooled Reactor (GIF SCWR) 2013–2014 seven-rod subchannel benchmark exercise. This study was motivated by the result of the benchmark exercise that all the CFD codes gave similar results to a subchannel code, which does not possess any sophisticated turbulence modeling. Initial findings were that the CFD codes generally underpredicted the wall temperatures on the B2 case in the region where the flow was supercritical. Therefore, it was decided to examine the effect of various turbulence model parameters to determine if a CFD code using the SST turbulence model could do a better job overall in predicting the wall temperatures of the benchmark experiments. A sensitivity study of seven parameters was done, and changes to two parameters were found to make an improvement.

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Sensitization of the SST Turbulence Model to Rotation and Curvature by Applying the Spalart–Shur Correction Term

Journal of Turbomachinery ◽

10.1115/1.3070573 ◽

2009 ◽

Vol 131 (4) ◽

Cited By ~ 139

Author(s):

Pavel E. Smirnov ◽

Florian R. Menter

Keyword(s):

Turbulent Flows ◽

Turbulence Model ◽

Transport Model ◽

Correction Term ◽

Computational Cost ◽

Turbulence Models ◽

Reynolds Stress Transport Model ◽

Wide Range ◽

Sst Model ◽

The One

A rotation-curvature correction suggested earlier by Spalart and Shur (1997, “On the Sensitization of Turbulence Models to Rotation and Curvature,” Aerosp. Sci. Technol., 1(5), pp. 297–302) for the one-equation Spalart–Allmaras turbulence model is adapted to the shear stress transport model. This new version of the model (SST-CC) has been extensively tested on a wide range of both wall-bounded and free shear turbulent flows with system rotation and/or streamline curvature. Predictions of the SST-CC model are compared with available experimental and direct numerical simulations (DNS) data, on the one hand, and with the corresponding results of the original SST model and advanced Reynolds stress transport model (RSM), on the other hand. It is found that in terms of accuracy the proposed model significantly improves the original SST model and is quite competitive with the RSM, whereas its computational cost is significantly less than that of the RSM.

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